1. Field of the Invention
The present invention relates to an improvement of a glass fiber bushing of the type which extends through a wall opening of a housing, preferably a gas-tight or air-tight metal housing, as described in the German DOS No. 32 44 867.
2. Description of the Prior Art
The present invention was particularly developed for receiver modules having photodiodes and components thereof, as well as for transmitting modules having solid-state lasers as components thereof which are employed in digital switching systems with glass fibers which conduct light pulses modulated with information. Over and above this, however, the invention is useable in all other glass fiber bushings of the general type set forth above. The outer diameter of the glass fiber, or of a glass fiber protective layer, is surrounded, at least close to the tip of the glass fiber, by the inner wall of the tube with so little play, for example by way of fixing with an adhesive or a solder metal, that the tube defines the position of the glass fiber, particularly the tip thereof. The tube is plugged through an elastic membrane of the wall opening in a region between the adjustment member and the component. A surface of the membrane is secured to the housing in the environment of the wall opening. Also, the end face of the adjustment member for adjusting the position of the tube and, therewith, the position of the glass fiber is secured to the exterior surface of the housing.
Given the earlier glass fiber bushing, the housing already has a protective function for the light-transmitting and/or light-receiving component attached thereto. The housing, in particular, is both light-tight and gas-tight or, respectively, air-tight. The component therein is not only protected against injurious gases, but condensation water can no longer collect therein over time, whereby condensation water would deteriorate the quality of the light coupling between the component and the tip of the glass fiber. The earlier housing also offers considerable protection for its internal parts, for example glass fiber and component, against mechanical destruction due to blows or, respectively, acceleration. A pulling on the glass fiber, generally quite unintentional, from the exterior of the earlier housing hardly changes the properties of the light coupling between the component and the glass fiber tip within the housing, despite the extremely critical adjustment that is necessary of the glass fiber tip relative to the most optically-active location of the component. The adjustment member of the earlier glass fiber bushing likewise permits a good adjustment of the glass fiber tip, particularly in the direction of the glass fiber axis, with reference to the optically-active location of the component. An adjustment of the glass fiber tip in the radial directions of movement (relative to the glass fiber) can likewise be achieved with the earlier glass fiber bushing, particularly with the assistance of a gripper of a micromanipulator, whereby, after the optimization of the optical coupling between component and glass fiber tip, the glass fiber can be glued to a certain block close to the diode with the assistance of an adhesive, cf. in this regard the DOS No. 32 44 882 discloses this particular aspect of the adjustment given the earlier glass fiber bushing.
Given the earlier glass fiber bushing, the adjustment member is soldered, without a fluxing agent, to the glass fiber and/or to the tube, particularly because the vapors of the fluxing agent arising during soldering can contaminate, specifically, the glass fiber tip and the optically-active location of the component and because a subsequent cleaning, i.e. removal of these contaminants, within the housing is difficult or, respectively, can produce slightly disruptive side effects.